The present invention is directed to novel peptides having an inhibitory effect on the release of gonadotropins by the pituitary in mammals, including humans and having an influence on the growth of cancerous tumors in humans. More specifically, the present invention relates to antagonistic analogs of luteinizing hormone-releasing hormone (LHRH), which have the structure: EQU pGlu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH.sub.2
salts thereof, and to pharmaceutical compositions and methods of use pertaining to these analogs.